When people donate to religious groups, it's tax-deductible. Churches don't pay property taxes on their land or buildings. When they buy stuff, they don't pay sales taxes. When they sell stuff at a profit, they don't pay capital gains tax. If they spend less than they take in, they don't pay corporate income taxes. Priests, ministers, rabbis and the like get "parsonage exemptions" that let them deduct mortgage payments, rent and other living expenses when they're doing their income taxes. They also are the only group allowed to opt out of Social Security taxes (and benefits).
MORE: http://www.washingtonpost.com/blogs/wonkblog/wp/2013/08/22/you-give-religions-more-than-82-5-billion-a-year/
